This comparative oncology program is designed to study spontaneously occurring tumors in domestic animals which can provide appropriate model systems for meaningful cancer research. Naturally occurring cancers closely resemble human cancers. The use of spontaneous tumors in relating research objectives to practical needs of basic and clinical human cancer research should result in information applicable to prevention and treatment of cancer in man. The core of the concept involves an Animal Tumor Clinic located in the veterinary medical teaching hospital at Colorado State University. The clinic provides animal care and diagnosis leading to therapy trials and related tumor biology studies. The proposed program utilizes group capabilities for studies of various therapy modalities: radiotherapy, chemotherapy, immunotherapy, surgery and combined methods. Studies of tumor and normal tissue response or toxicity to variable levels of treatment are made. The program embodies current concepts and collaborations provided by Colorado's medical community and the overall cancer research community. Along with the core programs outlined, additional protocols will be developed for in-depth studies on selected animal tumors.